1. Field of the Invention
This invention generally relates to methods and apparatus for bone resection to allow for the interconnection or attachment of various prosthetic devices with respect to the patient. More particularly, the present invention relates to the use of pivotable guide surfaces for arthroplasty and bone resection techniques.
2. Background Art
Different methods and apparatus have been developed in the past to enable a surgeon to remove bony material to create specifically shaped surfaces in or on a bone for various reasons including to allow for attachment of various devices or objects to the bone. Keeping in mind that the ultimate goal of any surgical procedure is to restore the body to normal function, it is critical that the quality and orientation of the cut, as well as the quality of fixation, and the location and orientation of objects or devices attached to the bone, is sufficient to ensure proper healing of the body, as well as appropriate mechanical function of the musculoskeletal structure.
In total knee replacements, for example, a series of planar and/or curvilinear surfaces, or “resections,” are created to allow for the attachment of prosthetic or other devices to the femur, tibia and/or patella. In the case of the femur, it is common to use the central axis of the femur, the posterior and distal femoral condyles, and/or the anterior distal femoral cortex as guides to determine the location and orientation of distal femoral resections. The location and orientation of these resections are critical in that they dictate the final location and orientation of the distal femoral implant. It is commonly thought that the location and orientation of the distal femoral implant are critical factors in the success or failure of the artificial knee joint. Additionally, with t any surgical procedure, time is critical, and methods and apparatus that can save operating room time, are valuable. Past efforts have not been successful in consistently and/or properly locating and orienting resections in a quick and efficient manner.
Early techniques for bone resection involved the drilling of location holes into the bone to be resected and then pinning a guide plate in a fixed position to the bone using these holes as shown, for example, in U.S. Pat. No. 4,718,413. The guide plate would include guide surfaces or guide slots for a guiding a planar oscillating saw blade to aid the surgeon in resecting the bone surfaces. Some guide plates have utilized guide pin slots that cooperate with retractable guide pins on the oscillating saw to define a path for moving the saw as described, for example, in U.S. Pat. No. 5,092,869. The need to insure proper orientation of the guide mechanism relative to the long access of the femur, for example, led to the generally accepted practice of inserting a long rod into the intermedullary canal within the femur as a fixed point of reference for the guide mechanism. U.S. Pat. No. 5,047,032 describes a resection technique that uses an intermedullary rod as a fixed pivot point for a milling bit or router that resects a circular path around the intermedullary rod in order to create a single resected surface on the end of the femur. U.S. Pat. Nos. 5,228,459, 5,571,100 and 5,653,714 and U.S. Publ. Appl. 2003/0045883A1 describe various resection guide systems in which some portion of the guide mechanism can be rotated into a desired position and then locked in that position to permit the guide mechanism to be aligned by the surgeon in multiple different fixed positions. U.S. Pat. No. 5,643,272, for example, describes embodiments of a profile based resection technique that utilizes guide surfaces that permit the surgeon to plunge and sweep the cutting profile of a cutting tool in an arc within the confines of the guide surfaces.
While the cutting profile of the cutting tool is retained in a plane defined by the guide surfaces, there is no guide for how the surgeon manipulates the cutting tool in a sweeping manner to define the arc(s) within that plane.